1. Technical Field
The present invention relates to a light-emitting device, an image forming apparatus, a display device, and an electronic apparatus.
2. Related Art
In a light-emitting device having EL (electroluminescent) elements, such as organic EL elements or inorganic EL elements, it is necessary to make a band of an emission spectrum narrow and to increase an amount of emitted light for the purpose of facilitating many applications thereof. As a light-emitting device that meets the above requirements, there is a light-emitting device having microcavities formed by arranging a dielectric mirror between EL elements and a substrate (refer to Japanese Patent No. 3274527). The light-emitting device is of a bottom emission type, and light from EL elements is transmitted through the substrate and is then emitted.
In a light-emitting device having EL elements, a substrate on which the EL elements are arranged is very thick. Therefore, from the point of view of increasing an amount of emitted light, a top-emission-type light-emitting device that causes light from EL elements to be emitted toward a side opposite to a substrate is preferred rather than a bottom-emission-type light-emitting device. In addition, even in the top-emission-type light-emitting device, it is necessary to further increase the amount of emitted light. In addition, in the case of using a light-emitting device having organic EL elements as an exposure unit of an electrophotographic image forming apparatus or as a display device that displays an image, it is necessary to further narrow a band of an emission spectrum. Here, a case considered in which a technique disclosed in Japanese Patent No. 3274527 is applied to a top-emission-type light-emitting device.
However, in the case of the top-emission-type light-emitting device to which the technique disclosed in Japanese Patent No. 3274527 is applied, it is necessary to form a dielectric mirror on EL elements formed on a substrate in manufacturing the top-emission-type light-emitting device, which may cause the EL elements (for example, light-emitting layer) to be greatly damaged. Since the light emission characteristics of the EL elements that are greatly damaged noticeably deteriorate, it is difficult to apply the technique disclosed in Japanese Patent No. 3274527 to the top-emission-type light-emitting device.